content: /**
   * Copyright (c) 2016-present, RxJava Contributors.
   *
   * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in
   * compliance with the License. You may obtain a copy of the License at
   *
   * http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software distributed under the License is
   * distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See
   * the License for the specific language governing permissions and limitations under the License.
   */
  
  package io.reactivex.observable.subjects;
  
  import java.util.concurrent.atomic.*;
  
  import io.reactivex.common.*;
  import io.reactivex.common.annotations.*;
  import io.reactivex.observable.*;
  
  /**
   * Represents a hot Completable-like source and consumer of events similar to Subjects.
   * <p>
   * All methods are thread safe. Calling onComplete multiple
   * times has no effect. Calling onError multiple times relays the Throwable to
   * the RxJavaPlugins' error handler.
   * <p>
   * The CompletableSubject doesn't store the Disposables coming through onSubscribe but
   * disposes them once the other onXXX methods were called (terminal state reached).
   * <p>History: 2.0.5 - experimental
   * @since 2.1
   */
  public final class CompletableSubject extends Completable implements CompletableObserver {
  
      final AtomicReference<CompletableDisposable[]> observers;
  
      static final CompletableDisposable[] EMPTY = new CompletableDisposable[0];
  
      static final CompletableDisposable[] TERMINATED = new CompletableDisposable[0];
  
      final AtomicBoolean once;
      Throwable error;
  
      /**
       * Creates a fresh CompletableSubject.
       * @return the new CompletableSubject instance
       */
      @CheckReturnValue
      public static CompletableSubject create() {
          return new CompletableSubject();
      }
  
      CompletableSubject() {
          once = new AtomicBoolean();
          observers = new AtomicReference<CompletableDisposable[]>(EMPTY);
      }
  
      @Override
      public void onSubscribe(Disposable d) {
          if (observers.get() == TERMINATED) {
              d.dispose();
          }
      }
  
      @Override
      public void onError(Throwable e) {
          if (e == null) {
              e = new NullPointerException("Null errors are not allowed in 2.x");
          }
          if (once.compareAndSet(false, true)) {
              this.error = e;
              for (CompletableDisposable md : observers.getAndSet(TERMINATED)) {
                  md.actual.onError(e);
              }
          } else {
              RxJavaCommonPlugins.onError(e);
          }
      }
  
      @Override
      public void onComplete() {
          if (once.compareAndSet(false, true)) {
              for (CompletableDisposable md : observers.getAndSet(TERMINATED)) {
                  md.actual.onComplete();
              }
          }
      }
  
      @Override
      protected void subscribeActual(CompletableObserver observer) {
          CompletableDisposable md = new CompletableDisposable(observer, this);
          observer.onSubscribe(md);
          if (add(md)) {
              if (md.isDisposed()) {
                  remove(md);
              }
          } else {
              Throwable ex = error;
              if (ex != null) {
                  observer.onError(ex);
              } else {
                  observer.onComplete();
              }
          }
      }
  
      boolean add(CompletableDisposable inner) {
          for (;;) {
              CompletableDisposable[] a = observers.get();
              if (a == TERMINATED) {
                  return false;
              }
  
              int n = a.length;
  
              CompletableDisposable[] b = new CompletableDisposable[n + 1];
              System.arraycopy(a, 0, b, 0, n);
              b[n] = inner;
              if (observers.compareAndSet(a, b)) {
                  return true;
              }
          }
      }
  
      void remove(CompletableDisposable inner) {
          for (;;) {
              CompletableDisposable[] a = observers.get();
              int n = a.length;
              if (n == 0) {
                  return;
              }
  
              int j = -1;
  
              for (int i = 0; i < n; i++) {
                  if (a[i] == inner) {
                      j = i;
                      break;
                  }
              }
  
              if (j < 0) {
                  return;
              }
              CompletableDisposable[] b;
              if (n == 1) {
                  b = EMPTY;
              } else {
                  b = new CompletableDisposable[n - 1];
                  System.arraycopy(a, 0, b, 0, j);
                  System.arraycopy(a, j + 1, b, j, n - j - 1);
              }
  
              if (observers.compareAndSet(a, b)) {
                  return;
              }
          }
      }
  
      /**
       * Returns the terminal error if this CompletableSubject has been terminated with an error, null otherwise.
       * @return the terminal error or null if not terminated or not with an error
       */
      public Throwable getThrowable() {
          if (observers.get() == TERMINATED) {
              return error;
          }
          return null;
      }
  
      /**
       * Returns true if this CompletableSubject has been terminated with an error.
       * @return true if this CompletableSubject has been terminated with an error
       */
      public boolean hasThrowable() {
          return observers.get() == TERMINATED && error != null;
      }
  
      /**
       * Returns true if this CompletableSubject has been completed.
       * @return true if this CompletableSubject has been completed
       */
      public boolean hasComplete() {
          return observers.get() == TERMINATED && error == null;
      }
  
      /**
       * Returns true if this CompletableSubject has observers.
       * @return true if this CompletableSubject has observers
       */
      public boolean hasObservers() {
          return observers.get().length != 0;
      }
  
      /**
       * Returns the number of current observers.
       * @return the number of current observers
       */
      /* test */ int observerCount() {
          return observers.get().length;
      }
  
      static final class CompletableDisposable
      extends AtomicReference<CompletableSubject> implements Disposable {
          private static final long serialVersionUID = -7650903191002190468L;
  
          final CompletableObserver actual;
  
          CompletableDisposable(CompletableObserver actual, CompletableSubject parent) {
              this.actual = actual;
              lazySet(parent);
          }
  
          @Override
          public void dispose() {
              CompletableSubject parent = getAndSet(null);
              if (parent != null) {
                  parent.remove(this);
              }
          }
  
          @Override
          public boolean isDisposed() {
              return get() == null;
          }
      }
  }
  